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3.4l turbo forged crank 4 bolt main caps by 3.6lvvt6spdgt
Started on: 09-26-2007 12:07 PM
Replies: 34
Last post by: Will on 11-05-2007 10:56 AM
3.6lvvt6spdgt
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Report this Post09-26-2007 12:07 PM Click Here to See the Profile for 3.6lvvt6spdgtSend a Private Message to 3.6lvvt6spdgtDirect Link to This Post
i am curently looking into having some forged cranks made.
if you interested in also getting one of these custom cranks that are a requirement for any turbo or SC 3.4L.
with a forged crank and my custom 4-6 bolt main caps you could get in the 400hp range for the 3.4l with a turbo setup and 21psi. you will get way more hp with more mods you do to the engine.
SO IF YOU WANT ONE OF THESE CRANKS AND SET OF MAIN CAPS LET ME KNOW AND I WILL POST THE COST AND TAKE ORDERS ONCE THEY ARE READY FOR PRODUCTION.
ALSO LET ME KNOW WHAT YOUR WILLING TO PAY SO I KNOW YOUR SERIOUS.
im not sure but i think this crank will work in the dohc engines to.

[This message has been edited by 3.6lvvt6spdgt (edited 09-26-2007).]

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Erik
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Report this Post09-26-2007 12:52 PM Click Here to See the Profile for ErikClick Here to Email ErikSend a Private Message to ErikDirect Link to This Post
got any pics of the caps?
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FieroWannaBe
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Report this Post09-26-2007 01:21 PM Click Here to See the Profile for FieroWannaBeClick Here to Email FieroWannaBeSend a Private Message to FieroWannaBeDirect Link to This Post
price range?
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Will
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Report this Post09-26-2007 01:55 PM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillDirect Link to This Post
Don't expect a low volume forged crank for less than $4000 unless it's adapted from something else.

BTW, the 400 WHP barrier has been broken with a stock crankshaft/2 bolt block... IOW, forged crank and six bolt caps are not necessary.

[This message has been edited by Will (edited 09-26-2007).]

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darkhorizon
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Report this Post09-26-2007 02:33 PM Click Here to See the Profile for darkhorizonSend a Private Message to darkhorizonDirect Link to This Post
Wouldnt you find another failure point in the motor before the crank wops out and snaps? Custom cranks, are HUGE HUGE money as pointed out by Will.
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SLOWnSTEADY
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Report this Post09-26-2007 05:19 PM Click Here to See the Profile for SLOWnSTEADYClick Here to Email SLOWnSTEADYSend a Private Message to SLOWnSTEADYDirect Link to This Post
IMO, the money would be better spent in MANY other places... on 21# of boost i dont think it would what engien you have, you should be hitting 400HP no problem. I was putting down more than that on about 14# with my 2.0L and hopw to get near that on about 10-12 pounds on my DOHC. I just dont see people spending a bunch of money on a forged crank and caps when you could probably do an entire DOHC or 3800SC swap with mods and make that much power MUCH easier and cheaper and have it be more reliable...

just my $.02

[This message has been edited by SLOWnSTEADY (edited 09-26-2007).]

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3.6lvvt6spdgt
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Report this Post09-27-2007 03:23 PM Click Here to See the Profile for 3.6lvvt6spdgtSend a Private Message to 3.6lvvt6spdgtDirect Link to This Post
i was thinking if there were atleast 10 pepole that would want the crank that i could work a deal with the company to sell these on a reagular basis.
im using a 95 camero 3.4l engine and a t70 turbo i would like to have a 400 hp daily driver. how can i do this with out blowing the engine?
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Dennis LaGrua
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Report this Post09-27-2007 03:40 PM Click Here to See the Profile for Dennis LaGruaClick Here to Email Dennis LaGruaSend a Private Message to Dennis LaGruaDirect Link to This Post
 
quote
Originally posted by Will:

Don't expect a low volume forged crank for less than $4000 unless it's adapted from something else.

BTW, the 400 WHP barrier has been broken with a stock crankshaft/2 bolt block... IOW, forged crank and six bolt caps are not necessary.



Will is correct. The stock 2.8/3.1/3.4 L crankshaft is fairly strong. Dyno tests showing 347 HP and 397 ft lbs of torque on a turbocharged 3.4L have already been done on an engine with stock internals. That YouTube vid was posted here not long ago. That same engine propelled Tiogas F-Body car to mid 13 second 1/4 mile times. I am not even sure if you could so easily get the 3.4L to make 400 HP and if you add a forged custom crank like a Moldex, then the connecting rods would prove to be the weak link. Then if you purchased forged rods like those from Carillo, the pistons would be the weak link. Then if you added Ross Forged racing pistons, the block still might be the weak link and you'd have already spent close to $3000 on internal parts getting to this point.
IMO. if you want 400 RELIABLE horsepower I believe that you would be better served chosing a 3800SC or a LT1 / LT 2..

------------------
87GT 3.4 Turbo- 0-60 5.2 seconds
2006 3800SC Series III swap in progress
Engine Controls, PCM goodies,
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" I'M ON THE LOOSE WITHOUT THE JUICE "

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engine man
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Report this Post09-27-2007 06:06 PM Click Here to See the Profile for engine manClick Here to Email engine manSend a Private Message to engine manDirect Link to This Post
the main caps i would like if they will work on a 3.4 DOHC the stock crank is stronger than you think as far as conecting rods go you just use small jurnal V8 chvey rods and have the big end narowed small then you need pistons with a .927 wrist pin
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Joseph Upson
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Report this Post09-27-2007 06:24 PM Click Here to See the Profile for Joseph UpsonClick Here to Email Joseph UpsonSend a Private Message to Joseph UpsonDirect Link to This Post
It would be much more practical to use the stock steel cranks found in the 3.5 and 3.9L engines, they are already stronger than the cast crank and you would only need to have the larger diameter crank pin turned down from 2.2" to 2" or better yet since higher power levels are involved you will likely be using custom pistons in which case you could leave it as is or have the crank offset ground for a slight increase in stroke, then use your current rods and have the piston pin appropriately located for the combo in the custom pistons. The crank regrind would run ~$200 so the stronger main caps would be a good investment but if I recall correctly GM has been fiddling with the main caps also making some of them steel already. I'll have to go back and identify which engines. It's not to discourage you but to help you avoid investing in improving the strength of parts that have resently been improved.

The 3.6L DOHC has steel caps, caps 1,2, and 3 are powder metal for the 3.5 and 3.9 which is supposed to be a stronger composite than cast iron and #4 is cast iron. The rods are all sinter forged metal so I would think adapting the newer parts would be a good stock upgrade.

[This message has been edited by Joseph Upson (edited 09-27-2007).]

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3.6lvvt6spdgt
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Report this Post09-27-2007 06:54 PM Click Here to See the Profile for 3.6lvvt6spdgtSend a Private Message to 3.6lvvt6spdgtDirect Link to This Post
i realy just want a 400hp 3.4l v6 fiero does any one have one? any one even close? if so let me know how.
here is a list of my current mods.

COILOVERS
OIL FILTER SANDWICH ADAPTER
KYB GR-2 GR2 SHOCKS STRUTS PONTIAC FIERO 84 - 87
255LPH FUEL PUMP
NEW - GT45 T4 Turbo - GT45 Y2004K - 4.1" Outlet
XS Power 60mm External Turbo Wastegate
EBAY BLOW OFF VALVE
84-87 HEAVY DUTY REAR SWAY BAR W/ MOUNTING HARDWARE
84-87 HEAVY DUTY 1" FRONT SWAYBAR W/ MOUNTING HARDWARE
84-88 CLUTCH PEDAL ASSEMBLY
WCF Fiero Dog-Bone
Long Tube headers with "Y" pipe (Steel)
85-88 MSD IGNITION COIL
WCF 3.4L Flywheel
WCF V6 Engine mount
WCF Trans mount left
WCF Trans mount right
Stage 3 Clutch and Pressure plate
Aluminum cradle bushings
A Arm Poly bushings upper and lower front
A Arm Poly bushings upper and lower rear
remanufactured 1995 3.4l camaro/firebird engine 0mi with predrilled starter holes

Upgrades ive been concidering
port and polished heads
cam and roller rockers
ecu chip
custom plenium intake.

[This message has been edited by 3.6lvvt6spdgt (edited 09-27-2007).]

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Report this Post09-27-2007 07:59 PM Click Here to See the Profile for Fiero BrickSend a Private Message to Fiero BrickDirect Link to This Post
Matt Hawkins has a turbocharged 3.4 DOHC fiero that made about 415 horsepower at the wheels @ 15psi or so last time he put it on the dyno.
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project34
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Report this Post09-27-2007 09:12 PM Click Here to See the Profile for project34Send a Private Message to project34Direct Link to This Post
Your previous post on this thread asks...
 
quote
Originally posted by 3.6lvvt6spdgt:
i realy just want a 400hp 3.4l v6 fiero does any one have one? any one even close? if so let me know how.

On the other hand, your first post on this thread states...
 
quote
Originally posted by 3.6lvvt6spdgt:
with a forged crank and my custom 4-6 bolt main caps you could get in the 400hp range for the 3.4l with a turbo setup and 21psi.



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Erik
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Report this Post09-28-2007 01:31 AM Click Here to See the Profile for ErikClick Here to Email ErikSend a Private Message to ErikDirect Link to This Post
 
quote
Originally posted by engine man:

the main caps i would like if they will work on a 3.4 DOHC the stock crank is stronger than you think as far as conecting rods go you just use small jurnal V8 chvey rods and have the big end narowed small then you need pistons with a .927 wrist pin


I agree the stock crank is strong enough IMO its the caps that need attention. Straps and studs will work but it would be nice to have a 4 bolt if there is the meat in the block to allow for it. I havent checked that yet

[This message has been edited by Erik (edited 09-28-2007).]

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3.6lvvt6spdgt
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Report this Post09-28-2007 01:41 AM Click Here to See the Profile for 3.6lvvt6spdgtSend a Private Message to 3.6lvvt6spdgtDirect Link to This Post
well if no one is realy interested in a forged crank then why did you look? if i can get a decent amont of owners wanting the forged crank then the cost for the cranks will be less. ak instead of ordering 1 crank i order 10+ and get a discount. that was the reason for this post.
and as far as the 4 bolt mains just have a maching shop make u some thay are simple to do.
then just mod you block to fit the new 4 bolt you would need to drill holes inthe block to except the extra bolts.

[This message has been edited by 3.6lvvt6spdgt (edited 09-28-2007).]

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The_Stickman2
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Report this Post09-28-2007 01:49 AM Click Here to See the Profile for The_Stickman2Click Here to visit The_Stickman2's HomePageClick Here to Email The_Stickman2Send a Private Message to The_Stickman2Direct Link to This Post
I say go for it. But if you are going the forged crank route maybe you should up your expectations. I don't think 500-550hp would be out of range with a turbo and a good FI system. Personally i would keep the compression ratio low to keep the possiblity of detonation down.
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Report this Post09-28-2007 02:09 AM Click Here to See the Profile for 3.6lvvt6spdgtSend a Private Message to 3.6lvvt6spdgtDirect Link to This Post
of course i would levs the engine at the stock compression ratio i belive i was off in my calculations for expected hp output.
for every # of bost you gain 8% hp
so if you had 180hp your 3.4l
180 x 0.08 = 14.4 x 8 = 115.2 + 180 = 295.2
180 x 0.08 = 14.4 x 14 = 201.6 + 180 = 381.6
180 x 0.08 = 14.4 x 21 = 302.4 + 180 = 482.4
just incase you dident notice you gain 14.4hp per # of bost on an engine with 180hp

[This message has been edited by 3.6lvvt6spdgt (edited 09-28-2007).]

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Report this Post09-28-2007 02:58 AM Click Here to See the Profile for goatnipples2002Click Here to visit goatnipples2002's HomePageClick Here to Email goatnipples2002Send a Private Message to goatnipples2002Direct Link to This Post
?

[This message has been edited by goatnipples2002 (edited 09-28-2007).]

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Report this Post09-28-2007 05:35 AM Click Here to See the Profile for FierobsessedClick Here to Email FierobsessedSend a Private Message to FierobsessedDirect Link to This Post
I don't see any real reason for an aftermarket forged crank, only because they already exist from GM, and aren't all that expensive.

A competant machine shop can modify one of these cranks to be a drop in replacment for the 3.4/3.1L engines.

P/N 12577484 - $321.47 at GMPartsdirect.com
A little teaser:
http://www.60degreev6.com/showthread.php?t=33620

However, Mains. There is the 3100-3400 which are better then stock. But that is all there is. So there is a potential market there.

Here, stock VS 3100/3400. Notice the bolts on the sides, they are meant to bolt to a structural oil pan, but I suppose a brace could be fabricated to tie them all together, The front three mains look like this, the rear is the same as stock, without side bolts unfortunatly.


And, yes, 3.1/3.4L and 3.4 DOHC cranks are perfectly interchangeable and basically the same.

[This message has been edited by Fierobsessed (edited 09-28-2007).]

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engine man
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Report this Post09-28-2007 05:50 AM Click Here to See the Profile for engine manClick Here to Email engine manSend a Private Message to engine manDirect Link to This Post
well I was intrested in the caps but i will go back to plan B and see if a set of 400 small block chevy 4 bolt caps can be made to work it looks like the bore size is with in a thousant just need to see if the block can take biger bolts and if the iner bolt are real close to lining up

[This message has been edited by engine man (edited 09-28-2007).]

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Will
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Report this Post09-28-2007 09:12 AM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillDirect Link to This Post
 
quote
Originally posted by Joseph Upson:

It would be much more practical to use the stock steel cranks found in the 3.5 and 3.9L engines, they are already stronger than the cast crank and you would only need to have the larger diameter crank pin turned down from 2.2" to 2" or better yet since higher power levels are involved you will likely be using custom pistons in which case you could leave it as is or have the crank offset ground for a slight increase in stroke, then use your current rods and have the piston pin appropriately located for the combo in the custom pistons. The crank regrind would run ~$200 so the stronger main caps would be a good investment but if I recall correctly GM has been fiddling with the main caps also making some of them steel already. I'll have to go back and identify which engines. It's not to discourage you but to help you avoid investing in improving the strength of parts that have resently been improved.

The 3.6L DOHC has steel caps, caps 1,2, and 3 are powder metal for the 3.5 and 3.9 which is supposed to be a stronger composite than cast iron and #4 is cast iron. The rods are all sinter forged metal so I would think adapting the newer parts would be a good stock upgrade.



I'd just use the 3500/3900 rods... What's the rod length on the VVT 3500?
Turning the crank pin is going to weaken the crank and GM made it bigger for a reason...
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Report this Post09-28-2007 11:25 AM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillDirect Link to This Post
 
quote
Originally posted by engine man:

well I was intrested in the caps but i will go back to plan B and see if a set of 400 small block chevy 4 bolt caps can be made to work it looks like the bore size is with in a thousant just need to see if the block can take biger bolts and if the iner bolt are real close to lining up



400 main journals are 2.65... Are the V6 journals 2.25?
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Report this Post09-28-2007 06:12 PM Click Here to See the Profile for Joseph UpsonClick Here to Email Joseph UpsonSend a Private Message to Joseph UpsonDirect Link to This Post
 
quote
Originally posted by Will:


I'd just use the 3500/3900 rods... What's the rod length on the VVT 3500?
Turning the crank pin is going to weaken the crank and GM made it bigger for a reason...


All version of the 3500 and the 3900 use 5.9" rods and although machining the rod journals down from 2.2" would make it weaker than its original strength it would still be at standard specs for the cast iron crank in terms of journal size and therefore still stronger than the cast iron crank. On the other hand if it's offset ground that would be a different story. I priced offset grinding at $200 and if you wanted metal added to maintain the stock journal diameter $400.

An important reminder regarding the 3500 and 3900 engine is that in the "What's new" description GM specifically stated that the cylinder bore was moved to allow for greater future displacement if I read it correctly and I believe I did. Heck, look at where they took the standard 2.8L block; 3.5L. The 07 3500 is different from the 04-06 3500 and has the block mods mentioned.

The journal diameter increase was made to stiffen the crank more and help reduce engine noise and I imagine to handle the 6400 rpm red line these engines have now.

[This message has been edited by Joseph Upson (edited 09-28-2007).]

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engine man
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Report this Post09-28-2007 07:57 PM Click Here to See the Profile for engine manClick Here to Email engine manSend a Private Message to engine manDirect Link to This Post
Will you are right the mains are 2.533 on the 3.4 and 2.65 on the 400 cant even use 350 caps i dont think any way maybe a main girdle if I can get some one to make one or maybe i can get 4 bolt caps from GM due to the aluminum bow tie block uses 4 bolt mains
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Report this Post09-28-2007 08:54 PM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillDirect Link to This Post
4 bolt caps for the 60 degree are discon. I was just checking on that recently.

 
quote
Originally posted by Joseph Upson:
All version of the 3500 and the 3900 use 5.9" rods and although machining the rod journals down from 2.2" would make it weaker than its original strength it would still be at standard specs for the cast iron crank in terms of journal size and therefore still stronger than the cast iron crank. On the other hand if it's offset ground that would be a different story. I priced offset grinding at $200 and if you wanted metal added to maintain the stock journal diameter $400.

An important reminder regarding the 3500 and 3900 engine is that in the "What's new" description GM specifically stated that the cylinder bore was moved to allow for greater future displacement if I read it correctly and I believe I did. Heck, look at where they took the standard 2.8L block; 3.5L. The 07 3500 is different from the 04-06 3500 and has the block mods mentioned.

The journal diameter increase was made to stiffen the crank more and help reduce engine noise and I imagine to handle the 6400 rpm red line these engines have now.



Exactly. 5.900 is a decently long rod. If building such an engine to take punishment, I would get custom pistons made with the correct compression height and pin diameter to be used with the factory crank/rods.
The big potential issue I see with cutting the crank pins is that of surface treatment. Do they have undercut rolled fillets? If so, turning or grinding with destroy that strengthening feature. How were the cranks heat treated when produced? Will you have the journals hardened/nitrided/hard chromed after you have them turned?

Also, are you sure the 3900 and big bore 3500 have the same length rods? In previous short stroke engines, GM has used the same pistons with longer rods in the smaller displacement. The '90 4.5 Caddy engine has the same comp height as the later 4.9 and longer rods than previous 4.5's. The 94-5 L99 4.3 litre LT1 based V8 has a 3" stroke and 5.940" conrods which give it the same compression height as a 350. The Vortec 4800 truck engine uses the same pistons as the 5300 and longer conrods to go with the shorter stroke.

The big bore block has a 99 mm bore from the factory. Not sure if you've noticed, but this is the same as an LS1, so ALL KINDS of piston forgings will be available for custom work.

[This message has been edited by Will (edited 09-28-2007).]

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Report this Post09-28-2007 09:50 PM Click Here to See the Profile for Joseph UpsonClick Here to Email Joseph UpsonSend a Private Message to Joseph UpsonDirect Link to This Post
 
quote
Originally posted by Will:

4 bolt caps for the 60 degree are discon. I was just checking on that recently.


Exactly. 5.900 is a decently long rod. If building such an engine to take punishment, I would get custom pistons made with the correct compression height and pin diameter to be used with the factory crank/rods.
The big potential issue I see with cutting the crank pins is that of surface treatment. Do they have undercut rolled fillets? If so, turning or grinding with destroy that strengthening feature. How were the cranks heat treated when produced? Will you have the journals hardened/nitrided/hard chromed after you have them turned?

Also, are you sure the 3900 and big bore 3500 have the same length rods? In previous short stroke engines, GM has used the same pistons with longer rods in the smaller displacement. The '90 4.5 Caddy engine has the same comp height as the later 4.9 and longer rods than previous 4.5's. The 94-5 L99 4.3 litre LT1 based V8 has a 3" stroke and 5.940" conrods which give it the same compression height as a 350. The Vortec 4800 truck engine uses the same pistons as the 5300 and longer conrods to go with the shorter stroke.

The big bore block has a 99 mm bore from the factory. Not sure if you've noticed, but this is the same as an LS1, so ALL KINDS of piston forgings will be available for custom work.



Good point, you've jarred my memory. The VVT 3500 crank carries a 3.00" stroke, as for whether the difference is in the rod or the piston is a tough call because the 3900 and 3500 are listed under the same part numbers for pistons and rods on GM parts direct and that can't be right. So either the difference is in the piston which it probably is or the rod. The 04-06 non VVT 3500 does have 5.9" rods as well as all of the 3900s. Fillets can be re established in the thicker crank and as for hardening who knows whether GM went through the trouble on an already stout crank. The larger crank pin diameter is already a benefit as far spreading the rod bearing load over a larger area and I didn't have a bit of trouble drilling depressions in it with a .20 cent drill bit from Harbor freight when securing my reluctor ring with set screws. I ran my turbo 3100 hard and the one thing that really stood out when I disassembled the engine aside from the piston wear was the lack of wear on the bearings, so the later bearings must be that much better than what was installed on the 2.8. Other than that, unless it's common practice to harden cranks that have been turned down for reuse in what will typically be a well driven daily driver I doubt very seriously it will be a problem. The stuff they are building the engines and components out of now is just that much better than the old, and any respectable machinist who really knows his buisness will let you know if there're extras you need to consider, it is his/her buisness to know.

[This message has been edited by Joseph Upson (edited 09-28-2007).]

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engine man
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Report this Post09-28-2007 10:04 PM Click Here to See the Profile for engine manClick Here to Email engine manSend a Private Message to engine manDirect Link to This Post
Well just looked to see if DOHC heads could be droped on a 3.9 but the bore spacing is 1.5 mm wider so i doubt the crank will work in a earler modle engine dam dam dam just cant do all the hot rod stuff
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Erik
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Report this Post09-28-2007 10:47 PM Click Here to See the Profile for ErikClick Here to Email ErikSend a Private Message to ErikDirect Link to This Post
 
quote
Originally posted by engine man:

Will you are right the mains are 2.533 on the 3.4 and 2.65 on the 400 cant even use 350 caps i dont think any way maybe a main girdle if I can get some one to make one or maybe i can get 4 bolt caps from GM due to the aluminum bow tie block uses 4 bolt mains



My machinist says he can make me a set of straps that will be as strong as a 4 bolt cap without the trouble ..of course you would be using studs
He makes them for stock car guys all the time who are running 500HP SB engines and they hold up real well. He can also make me some billet 4 bolt caps but the cost will be higher of course.
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Report this Post09-28-2007 11:40 PM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillDirect Link to This Post
 
quote
Originally posted by Joseph Upson:
The 04-06 non VVT 3500 does have 5.9" rods as well as all of the 3900s.



Those two engines have the same stroke and block deck, of course, so they're naturally going to have the same rod length. Given GM's history with short stroke/long rod combos and the fact that powdered metal is easier to work than casting, I wouldn't be surprised at all if the VVT 3500 had longer rods than the 3900 by about 0.157.

[This message has been edited by Will (edited 09-28-2007).]

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Joseph Upson
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Report this Post09-29-2007 11:51 AM Click Here to See the Profile for Joseph UpsonClick Here to Email Joseph UpsonSend a Private Message to Joseph UpsonDirect Link to This Post
 
quote
Originally posted by Will:


Those two engines have the same stroke and block deck, of course, so they're naturally going to have the same rod length. Given GM's history with short stroke/long rod combos and the fact that powdered metal is easier to work than casting, I wouldn't be surprised at all if the VVT 3500 had longer rods than the 3900 by about 0.157.



I don't know Will, they kept the same rod between the 3" and 3.31" stroke cranks in the older motors. On a side bar the newer heads found on the VVT engines are phenominal in terms of their potential for air flow, I have an extra set of 3900 heads and can't help but admire the port design after the LS1 and LS6 heads and the valve sizes. Since the pistons have floating pins it makes things a bit easier to swap around. I would love to take that 3" stroke crank motor port the heads and turn it into about an 8 to 9K screamer, not sure a stock flywheel could handle that though.

[This message has been edited by Joseph Upson (edited 09-29-2007).]

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Lilchief
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Report this Post09-29-2007 12:30 PM Click Here to See the Profile for LilchiefSend a Private Message to LilchiefDirect Link to This Post
http://www.jbodyperformance...Name=JP0412&genName=
Here's a forged crank from J Body, cost more than GM though. They also had an article about a 750hp ecotec that I didn't read, might be of interest.

------------------

85 GT 3.4
14.9 @ 90 1.9 60' Old TH125/3.06
Unknown New 4T60/3.42

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Joseph Upson
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Report this Post09-29-2007 01:39 PM Click Here to See the Profile for Joseph UpsonClick Here to Email Joseph UpsonSend a Private Message to Joseph UpsonDirect Link to This Post
 
quote
Originally posted by Lilchief:

http://www.jbodyperformance...Name=JP0412&genName=
Here's a forged crank from J Body, cost more than GM though. They also had an article about a 750hp ecotec that I didn't read, might be of interest.



I saw that crank on one of the other Forums where it was alleged that it is a GM crank from the 04 up 3500 that was machined to the current specs. They never referred to it as brand new so either they are casting a new crank which I'm not sure it would be legal for them to do at this point as far as patents are concerned or it's a modified GM crank which again would make the most sense. The price would certainly be accurate if you purchased the crank new from GM at around $400 then reworked it and added retail mark up. The surface that the OE removable sensor ring rides on is the same diameter as the circle area on the earlier design crank that the notches are cut into.
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3.6lvvt6spdgt
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Report this Post11-04-2007 06:45 PM Click Here to See the Profile for 3.6lvvt6spdgtSend a Private Message to 3.6lvvt6spdgtDirect Link to This Post
http://www.jbodyperformance...d=412&catName=JP0412
they say it works for the 2.8 3.1 & 3.4l
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Joseph Upson
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Report this Post11-04-2007 08:32 PM Click Here to See the Profile for Joseph UpsonClick Here to Email Joseph UpsonSend a Private Message to Joseph UpsonDirect Link to This Post
It's a modified stock forged 3500/3900 steel crank as confirmed by someone who purchased one from that company and actually had some component mismatch problems, it would be much more practical to start with a 3500 short block than to modify the crank to retrofit back to the smaller displacement engine if you are seeking a power increase. The crank alone costs more than what low mileage 3500 and 3900 engines can be purchased for now so you may as well get your moneys worth, and probably more practical still to relieve the earlier blocks to use the unmodified crank.

They are able to modify various aspects of the crank because they have to rework it from its original state to work in the 3.4 and below from the start, hince the comment about the journals being made in such away it can be offset ground to increase stroke, in other words from the 2.25" stock crank pin to the earlier 2" dia.

[This message has been edited by Joseph Upson (edited 11-04-2007).]

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Will
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Report this Post11-05-2007 10:56 AM Click Here to See the Profile for WillClick Here to Email WillSend a Private Message to WillDirect Link to This Post
 
quote
Originally posted by Joseph Upson:


I don't know Will, they kept the same rod between the 3" and 3.31" stroke cranks in the older motors. On a side bar the newer heads found on the VVT engines are phenominal in terms of their potential for air flow, I have an extra set of 3900 heads and can't help but admire the port design after the LS1 and LS6 heads and the valve sizes. Since the pistons have floating pins it makes things a bit easier to swap around. I would love to take that 3" stroke crank motor port the heads and turn it into about an 8 to 9K screamer, not sure a stock flywheel could handle that though.



The rods in the 2.8 and 3.1 are forgings, GM has taken on the above mentioned propensity for longer conrods since they started making powdered metal rods.
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